The present invention relates to a connection terminal, and more particularly to a connection terminal assembly that connects a fluid pressure sensor and a control circuit board.
In connection terminals which connect fluid pressure sensors and control circuit boards, there has been a connection terminal (a fitting-type connection terminal) that achieves an electrical contact between a male terminal and a female terminal by fitting the male terminal into the female terminal. In this connection terminal, the male terminal is an axial member formed with electric conductor such as metal, and the male terminal is inserted and fitted into the female terminal. The connection terminal, therefore, ensures electrical conductivity.
Generally, the connection terminal is not so large, therefore, an axial diameter of the male terminal tends to be small, or an axis of that tends to be thin. Further, a length of the axis of male terminal is substantially long, in order for the male terminal to be inserted and fitted into the female terminal. Because of this, the strength of the male terminal tends to become lower. Then, if positioning or locating between the male and female terminals at the insertion or the fitting is not accurate, there may arise damage to the male terminal or ill effects on the male terminal by interference between the male terminal and a housing of the female terminal. Thus, for the fitting-type connection terminal, it is necessary that the positioning between the male and female terminals takes place accurately at the insertion or the fitting. In other words, the male terminal needs inserting and fitting into the female terminal accurately.
With respect to the positioning, in a case where only one male terminal and one female terminal are connected to each other (that is, only one pair of the male and female terminals is connected to each other), the positioning thereof is easy and both terminals can be connected to each other accurately. On the other hand, there is a case where an equal numbers of a plurality of the male and female terminals are provided in an apparatus, and each of the male terminals is fixed to one housing, and each of the female terminals is fixed to the other housing, then both housings are connected to each other so as to electrically connect the male and female terminals. In this case, since each terminal is fixed to the housing, each male terminal is necessarily connected to the respective female terminals at the same time or all together. It is therefore impossible to connect the male and female terminals one by one. For this reason, each terminal has to be positioned at the housing accurately. However, in fact, it is difficult that each of the plurality of the male and female terminals is positioned or located on the housing accurately.
In particular, in a case of a fluid pressure sensor for braking device or system, it is required that a plurality of terminals should be provided and arranged on a housing formed by aluminum die casting, in order to sense fluid pressures at a plurality of measurement points set on a hydraulic circuit and to output them to a control circuit. In this case, to fix the terminals to the housing, holes (press-fitting holes) are formed on the housing, and the terminals are press-fitted into the press-fitting holes on the housing. With respect to the press-fitting hole, it is formed by drilling, and therefore its shape becomes round or circular. Because of this, there is a possibility that the terminal may rotate or turn in the press-fitting hole.
To avoid the rotation of the terminal, the terminal is fixed to the housing by caulking the press-fitting hole after the terminal is press-fitted into the press-fitting hole. However, owing to the caulking, even if the press-fitting hole is positioned on the housing accurately before the caulking, position of the terminal may become misaligned or position deviation of the terminal may occur during the caulking. To overcome this, the press-fitting hole may be formed into square shape by casting. However, in that case, there is a possibility that working fluid may leak from corners of the square press-fitting hole due to lack of sealing. Thus, the square press-fitting hole is not suitable for the fluid pressure sensor which senses the fluid pressure whose pressure is exerted inside the press-fitting hole.
Accordingly, although there is no other way than to form the press-fitting hole into round shaped hole, and to caulk the press-fitting hole after the terminal is press-fitted into the press-fitting hole, in fact, it is difficult to eliminate deviation of an actual position of the terminal from a target fixing position of the press-fitting hole when fixing the terminal to the housing, due to position error of the press-fitting hole and the above-mentioned position deviation of the terminal, occurred during the caulking.
As described above, for the terminal of the braking device and the like, in which there are the plurality of male terminals disposed on one member and the equal numbers of plurality of female terminals disposed on the other member and then the one member connects to the other member to electrically connect the male and female terminals, the positioning of the terminal is important because the plurality of the male and female terminals are connected to each other at once or all together. However, as mentioned above, it is extremely difficult that each of the plurality of male and female terminals is positioned or located accurately without misalignment or deviation of the terminal. Further, even if the positioning is made accurately, it results in deterioration in assembly performance.
For the above problems, Published Patent Application, Japanese translation of PCT international application 2002-542107 (hereinafter is referred to as “JP2002-542107”) corresponding to US6789415 B1, shows a way of the electrical connection of the terminal. In the JP2002-542107, the fitting-type terminal is not used at an electrical contact portion. Electrical connection is established by means of spring contact pin, that contacts an opposed contact face by spring force (this type terminal is called a contact-type terminal). By this way of the contact (by the contact-type terminal), the accurate positioning between terminals becomes unnecessary.